Mobile electronic devices may include functionality for determining a geographic location of the device. The location may be determined using various different techniques. For example, a mobile device may use satellite based positioning system such as a Global Positioning System (GPS) that determines the position based on received signals from a number of satellites, an assisted-GPS (A-GPS) system which uses a combination of GPS and wireless network transmitter infrastructure information to determine a location, a network-only based location system using network transmitter locations to determine a location, or a handset-based system where the mobile device may have knowledge of transmitter locations and can provide a location estimate but may utilize location databases retrievable from a network. While some location techniques may work well in outdoor environments, they require reception of a signal or signals from a satellite, which may be difficult in various locations or conditions such as indoor applications. In addition, location databases used by location services, either network or mobile device based, may not have accurate network information to be able to determine a location in a changing wireless environment and where network or satellite based location services are not available or do not provide sufficient resolution.
FIG. 1 depicts determining the location of the mobile device using transmitter locations. As depicted, a number of Wi-Fi routers 102a, 102b, 102c (referred to collectively as routers 102) transmit RF signals, which are received by a user's mobile device, depicted as user 104. If the location of the routers 102 is known, it is possible to estimate the user's location based on the known router locations. In this example the user's location is depicted as being estimated as a simple centroid of the router locations. It is possible to incorporate the received signal strength, or other means of estimating a distance from a receiver such as time pulse, from the different routers 102 in order to improve the accuracy of the estimated location. Further, although described as being Wi-Fi routers, the same technique may use different transmitters such as cellular transmitters and Bluetooth transmitters or similar devices from which the strength or the pulse of an RF signal may be measured.
As described above, it is possible to estimate a user's location, or more particularly a user's mobile computing device, using the locations of transmitters. However, these techniques require that the locations of transmitters be available to the mobile device. It is possible to maintain a list of transmitters that were observed by user devices and their location when the observations were made. Although this technique can provide the locations for transmitters, it has a relatively large latency from when transmitters are first observed and their locations are propagated to location databases and then to mobile devices.
As such, it is difficult to determine a mobile device's location using the locations of transmitters whose geographical locations change periodically. For example, during a conference a hotel or conference organizer may setup a number of temporary Wi-Fi transmitters to provide capacity to service a temporary capacity influx. Although the conference organizer or hotel may know the locations of the temporary transmitters, the transmitter locations typically would not propagate into a location database used by the mobile device quickly enough to be of use to help location services. That is, by the time the location data for the conference transmitters is available in the location database, the conference may be completed. In addition, the temporary transmitters may have been previously used at another location which can provide incorrect location data if propagated to the location database.
It is desirable to have an additional or alternative method for determining a mobile devices' location using temporary location data of transmitters.